Three-axis machine structure

Abstract

A mechanical control structure is used with a machine, such as a machine tool. The control structure includes a base and a tool support member connected by a linkage assembly having three linkages arranged in a triangular pattern. The linkages cooperate to prevent rotational movement of the tool support member relative to the base along any of the three rotational axes. Three linear actuators are also connected between the base and the tool support member to move the tool support member relative to the base along a predetermined path.

What is claimed: 
     
       1. A mechanical control structure for use in cooperation with a machine to limit the rotational movement of an object along the rotational axes as the object is moved by the machine through three dimensional space along a predetermined path, comprising: a base structure;   an object supporting member; and   a linkage assembly comprising a plurality of linkages, each linkage having: a first link pivotably mounted to one of the base structure or the object supporting member such that the first link is constrained to pivot about an axis with one degree of freedom, the first link including a reinforced region to provide greater structural rigidity; and   a second link having a pair of arm members, each arm member being connected between a pivot joint on the first link and a pivot joint on the other of the base structure or the object supporting member, wherein the linkage assembly restricts movement of the object supporting member relative to the base structure along the rotational axes, further wherein the arm members within each pair of arm members are configured to remain parallel to one another as the object supporting member moves relative to the base structure.     
     
     
       2. The mechanical control structure as recited in claim 1, wherein the first link is pivotably mounted to the base structure. 
     
     
       3. The mechanical control structure as recited in claim 1, wherein the linkage assembly includes three linkages. 
     
     
       4. The mechanical control structure as recited in claim 3, wherein the linkages are arranged in a generally triangular pattern. 
     
     
       5. The mechanical control structure as recited in claim 3, wherein the pivot joints on the first link and on the other of the base structure or the object supporting member permit pivotable motion of each member with at least two degrees of freedom. 
     
     
       6. The mechanical control structure as recited in claim 5, wherein the arm members within each pair of arm members are equal length. 
     
     
       7. The mechanical control structure as recited in claim 5, wherein all arm members are equal length. 
     
     
       8. The mechanical control structure as recited in claim 4, wherein the first link and the second link both extend laterally outward such that they are pivotably joined at a location lying laterally outward from the locations at which the first and second links are connected to the base structure and the object supporting structure. 
     
     
       9. An apparatus that can be used to move an object through three dimensional space while restricting the object from rotating along the three rotational axes, comprising: a base structure;   an object supporting member;   a linkage assembly including three linkages, each linkage having: a first link pivotably mounted to one of the base structure or the object supporting member such that the first link is constrained to pivot about an axis with one degree of freedom, the first link including a reinforced region to provide greater structural rigidity; and   a second link having a pair of arm members, each arm member being connected between a pivot joint on the first link and a pivot joint on the other of the base structure or the object supporting member, wherein each pair of arm members remains parallel to permit the linkage assembly to prevent movement of the object supporting member relative to the base structure along the rotational axes; and   a plurality of linear actuators oriented to move the object supporting member relative to the base structure.     
     
     
       10. The apparatus as recited in claim 9, wherein each linear actuator is pivotably connected to both the base structure and to the object supporting member. 
     
     
       11. The apparatus as recited in claim 10, wherein the plurality of linear actuators includes three linear actuators. 
     
     
       12. The apparatus as recited in claim 9, wherein the first link of each linkage includes a reinforced region. 
     
     
       13. The apparatus as recited in claim 12, wherein the first link and second link are oriented such that each pivot joint is disposed laterally outward from the locations at which each linkage is connected to the base structure and to the object supporting member. 
     
     
       14. The apparatus as recited in claim 13, further comprising a tool mounted to the object supporting member and a fixture for holding a workpiece, wherein the linear actuators may be controlled to move the tool along a predetermined path with respect to the fixture. 
     
     
       15. The apparatus as recited in claim 14, wherein the tool and the fixture are mounted between the base structure and the object supporting member. 
     
     
       16. The apparatus as recited in claim 14, wherein the tool is oriented to interact with a workpiece mounted to the fixture, and the fixture is located externally of the base structure and object supporting member. 
     
     
       17. A mechanical control structure for use in cooperation with a machine to limit the rotational movement of an object along the rotational axes as the object is moved by the machine through three dimensional space along a predetermined path, comprising: a base structure;   an object supporting member; and   a linkage assembly comprising a plurality of linkages, each linkage having: a first link pivotably mounted to one of the base structure or the object supporting member such that the first link is constrained to pivot about an axis with one degree of freedom; and   a second link having a pair of arm members, each arm member being connected between a pivot joint on the first link and a pivot joint on the other of the base structure or the object supporting member, wherein the linkage assembly restricts movement of the object supporting member relative to the base structure along the rotational axes, further wherein the first link and the second link both extend laterally outward such that they are pivotably joined at a location lying laterally outward from the locations at which the first and second links are connected to the base structure and the object supporting structure, wherein the arm members of each second link are of equal length and remain parallel to each other as the object supporting member moves relative to the base structure.     
     
     
       18. The mechanical control structure as recited in claim 17, further comprising a plurality of actuators oriented to move the object supporting member relative to the base structure.